Multiple cylinder pump mechanisms are used in process pumps for delivering large delivery streams or at high pressures. Usually, diaphragm pump heads are used as the pump heads in this case. Since the diaphragms used therein are only capable of limited deflection, diaphragm pump heads having very large diameters are required for large delivery volumes. If such large diaphragm pump heads are to be operated using a multiple cylinder mechanism, the intervals of the pump head holders and/or the cylinders must therefore also be large enough. In typical pump mechanisms, the individual cylinders are typically situated in parallel and mounted horizontally on a crankshaft which also lies horizontally. In this case, a large cylinder interval in the connection area for the pump heads also requires a large mounting interval on the crankshaft. In the event of multiple cylinders and large pump heads, the crankshaft must be designed correspondingly long. This in turn requires special properties of the crankshaft, in particular in regard to stability and flexural strength. High costs in production and storage result due to this and due to the large amount of space required. Efforts to develop high-performance pump mechanisms which require less space have resulted from this.
A multiple cylinder diaphragm pump, in which the cylinder pistons are mounted on a single eccentric on a crankshaft, is known from German Utility Model DE G8521520.1 U1. The individual cylinders are situated radially around the crankshaft in this case. The crankshaft itself is accordingly comparatively short. In order to achieve uniform superposition of the partial delivery streams of the individual cylinders, the angles at which the cylinders stand to one another are distributed uniformly around 360°. The radial arrangement of the cylinders is connected to significant disadvantages, however. Firstly, the overall pump is thus relatively protrusive, and the space required by the pump is still unsatisfactory, in addition, the accessibility of the rear cylinders is significantly restricted when the pump is installed. Furthermore, the piping requires a special outlay.
From this background, it is the object of the present invention to specify a pump mechanism which is especially compact and has a short crankshaft while simultaneously having good accessibility of the individual cylinders.